Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/45—Compounds containing sulfur and halogen, with or without oxygen
  • C01B17/4507—Compounds containing sulfur and halogen, with or without oxygen containing sulfur and halogen only
  • C01B17/4515—Compounds containing sulfur and halogen, with or without oxygen containing sulfur and halogen only containing sulfur and fluorine only
  • C01B17/453—Sulfur hexafluoride
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/10—Halides or oxyhalides of phosphorus
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/08—Compounds containing halogen
  • C01B33/107—Halogenated silanes
  • C01B33/10705—Tetrafluoride
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B35/00—Boron; Compounds thereof
  • C01B35/06—Boron halogen compounds
  • C01B35/061—Halides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B9/00—General methods of preparing halides
  • C01B9/08—Fluorides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G41/00—Compounds of tungsten

Definitions

• the present invention relates to a method for preparing a gaseous metallic fluoride by reacting a metal or metallic oxide with a fluorine gas or nitrogen trifluoride gas.
• a gaseous metallic fluoride of the present invention means a metallic fluoride which is in a gaseous state in the vicinity of a temperature at which a metal or metallic oxide is reacted with a fluorine gas or nitrogen trifluoride gas.
• gaseous metallic fluoride examples include compounds such as tungsten hexafluoride (WF 6 ), molybdenum hexafluoride (MoF 6 ), antimony pentafluoride (SbF 5 ), niobium pentafluoride (NbF 5 ), tantalum pentafluoride (TaF 5 ), titanium tetrafluoride (TiF 4 ), silicon tetrafluoride (SiF 4 ), germanium tetrafluoride (GeF 4 ) and arsenic trifluoride (AsF 3 ).
• WF 6 tungsten hexafluoride
• MoF 6 molybdenum hexafluoride
• SbF 5 antimony pentafluoride
• NbF 5 niobium pentafluoride
• TaF 5 tantalum pentafluoride
• TiF 4 titanium tetrafluoride
• SiF 4 silicon
• WF 6 , MoF 6 and the like are expected as raw materials of electrodes for semiconductors.
• tungsten silicide (WSi 2 ) and molybdenum silicide (MoSi 2 ) which can be prepared from WF 6 and MoF 6 as raw materials are noticed as wire materials for large scale integrated circuits (LSI).
• LSI large scale integrated circuits
• the above-mentioned gaseous metallic fluorides, inclusive of WF 6 and MoF 6 are used as various fluorinating agents and as optical materials.
• the gaseous metallic fluoride has been generally prepared by a method which comprises contacting/reacting a metal or metallic oxide with a fluorine (F 2 ) gas or nitrogen trifluoride (NF 3 ) gas at a high temperature of some hundreds centigrade degrees.
• a metal or metallic oxide with a fluorine (F 2 ) gas or nitrogen trifluoride (NF 3 ) gas at a high temperature of some hundreds centigrade degrees.
• F 2 fluorine
• NF 3 nitrogen trifluoride
• the F 2 gas is diluted with an inert gas such as a nitrogen (N 2 ) gas or argon (Ar) gas so that the concentration of the F 2 gas may be in the range of about 10 to 30% by volume, when used in the above-mentioned contact reaction.
• an inert gas such as a nitrogen (N 2 ) gas or argon (Ar) gas so that the concentration of the F 2 gas may be in the range of about 10 to 30% by volume, when used in the above-mentioned contact reaction.
• the F 2 gas is very toxic, and therefore it is advantageous to use NF 3 from the viewpoint of safety, though cost increases a little.
• metal or metallic oxide will be called “metal or the like” inclusively.
• the produced gaseous metallic fluoride is led out of the reaction system and is then cooled at a temperature less than its boiling point in order to collect the product. Therefore, a carrier gas is necessary in the reaction. Since the carrier gas is introduced together with the F 2 gas or NF 3 gas into a reactor, an inert gas such as a nitrogen (N 2 ) gas, helium (He) gas or argon (Ar) gas is usually used as the carrier gas.
• N 2 nitrogen
• He helium
• Ar argon
• the metal or the like When the metal or the like is reacted with the F 2 gas or NF 3 gas (hereinafter referred to sometimes as "F 2 gas or the like"), the metal or the like is usually used in the form of powder so as to promptly and effectively perform the contact of the metal or the like with the F 2 gas or the like.
• This reaction is carried out by introducing the F 2 gas or NF 3 gas into the powder layer of the metallic oxide on a fluidized bed or fixed bed disposed in the reactor.
• the diluted F 2 gas or the like passes through the layer of the metallic powder or the like being fluidized, and therefore the fine powder of the metal or the like is entrained in the produced gaseous metallic fluoride, with the result that the purity of the product deteriorates. Furthermore, the yield of the product is limited to about 80% or so based on the F 2 gas, and also in this point, the above-mentioned method is insufficient.
• the reaction of the metallic powder or the like and the F 2 gas or the like is performed only on the surface of the layer of the metallic powder or the like, and thus the contact area of the metal powder or the like with the F 2 gas or the like is restricted, so that the yield is inconveniently low.
• the produced gaseous metallic fluoride is contaminated with plenty of the unreacted F 2 gas or the like.
• the metal powder or the like is more and more finely ground, and the finely ground metal powder is entrained in the produced gas, which leads to the deterioration in the product purity.
• An object of the present invention is to provide a method for preparing a gaseous metallic fluoride by which the contamination of the gaseous metallic fluoride with metal powder is prevented and by which the desired gaseous metallic fluoride can be manufactured in high yield and at low cost.
• the present invention is directed to a method for preparing a gaseous metallic fluoride by reacting a metal or its oxide with a fluorine gas or nitrogen trifluoride gas, the aforesaid method being characterized by comprising the steps of selecting the metal (M) or its oxide; mixing the metal (M) or its oxide with a molding auxiliary comprising a solid metallic fluoride which does not react with fluorine and nitrogen trifluoride; molding the resulting mixture under pressure; and contacting the molded pieces with the fluorine gas or nitrogen trifluoride gas, while the molded pieces are heated.
• the gaseous metallic fluoride is a compound represented by MFm wherein M is at least one simple metal selected from the group consisting of metals in the groups IIIA, IIIB, IVA, IVB, VA, VB, VIA and VIB of the periodic table, and m is an integer of 3 to 6.
• the gaseous metallic fluoride is at least one compound selected from the group consisting of tungsten hexafluoride (WF 6 ), molybdenum hexafluoride (MoF 6 ), antimony trifluoride (SbF 3 ), antimony pentafluoride (SbF 5 ), niobium pentafuoride (NbF 5 ), arsenic trifluoride (AsF 3 ), phosphorus trifluoride (PF 3 ), boron trifluoride (BF 3 ), tantalum pentafuoride (TaF 5 ), titanium tetrafluoride (TiF 4 ), silicon tetrafluoride (SiF 4 ), germanium tetrafluoride (GeF 4 ), sulfur hexafluoride (SF 6 ) and uranium hexafluoride (UF 6 ).
• WF 6 tungsten hexafluoride
• MoF 6
• the solid metallic fluoride as the molding auxiliary which does not react with fluorine and nitrogen trifluoride is at least one compound selected from the group consisting of fluorides of metals in the groups IA, IIA and IIIB of the periodic table.
• the solid metallic fluoride is at least one compound selected from the group consisting of lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), rubidium fluoride (RbF), cesium fluoride (CsF), beryllium fluoride (BeF 2 ), magnesium fluoride (MgF 2 ), calcium fluoride (CaF 2 ), strontium fluoride (SrF 2 ), barium fluoride (BaF 2 ), aluminum fluoride (AlF 3 ), gallium fluoride (GaF 3 ) indium fluoride (InF 3 ), thallium fluoride (TlF 3 ) and aluminum sodium fluoride (Na 3 AlF 6 ).
• LiF lithium fluoride
• NaF sodium fluoride
• KF potassium fluoride
• RbF rubidium fluoride
• CsF cesium fluoride
• BeF 2 beryllium fluoride
• MgF 2 magnesium fluor
• the simple metal or its oxide which is the raw material is a simple metal or its oxide corresponding to the above-mentioned gaseous metallic fluoride.
• the metal or its oxide which is the raw material is mixed with the molding auxiliary, the amount of the metal or its oxide being in the range of 30 to 70% by weight. Afterward, the mixture is molded in a shape of cylinder, ring or chrysanthemum having a typical diameter of about 5 to 15 mm under a pressure of 0.5 to 10 t/cm 2 .
• the reaction of the thus molded pieces with the fluorine gas or nitrogen trifluoride gas is carried out at a temperature of 150° to 700° C. under a pressure of 1 to 10 kg/cm 2 for a period of 1 to 20 hours. At this time, it is preferred that the molded pieces are disposed as a filler layer in a reactor and the fluorine gas or nitrogen trifluoride gas is caused to pass through this layer.
• the molded pieces are subjected to a heating treatment in a reducing gas atmosphere at a temperature of 500° to 850° C. for a period of 1 to 500 hours.
• a gaseous metallic fluoride which can be prepared in the present invention is a fluoride which can be synthesized by usually reacting fluorine or nitrogen trifluoride (hereinafter referred to simply as “fluorine or the like”) with a metal or metallic oxide (hereinafter referred to simply as “metal or the like”), and the above-mentioned fluoride is in a gaseous state at a reaction temperature at which the simple metal or the like is reacted with the F 2 gas or the like, for example, at a temperature of 300° C. or more.
• fluorine or nitrogen trifluoride hereinafter referred to simply as "fluorine or the like
• metal or metallic oxide hereinafter referred to simply as “metal or the like
• Examples of such a fluoride compound include tungsten hexafluoride (WF 6 ), molybdenum hexafluoride (MoF 6 ), antimony pentafluoride (SbF 5 ), antimony trifluoride (SbF 3 ), niobium pentafluoride (NbF 5 ), tantalum pentafluoride (TaF 5 ), titanium tetrafluoride (TiF 4 ), silicon tetrafluoride (SiF 4 ), silicon hexafluoride (SiF 6 ), germanium tetrafluoride (GeF 4 ), arsenic trifluoride (AsF 3 ), uranium hexafluoride (UF 6 ), phosphorus trifluoride (PF 3 ), boron trifluoride (BF 3 ) and sulfur hexafluoride (SF 6 ).
• WF 6 tungsten hexafluoride
• the metal used in the present invention is a metal constituting the above-mentioned gaseous metallic fluoride.
• This metal is selected from metals in the groups IIIA, IIIB, IVA, IVB, VA, VB, VIA and VIB of the periodic table, and preferable typical examples of the simple metal include tungsten (W), molybdenum (Mo), antimony (Sb), niobium (Nb), arsenic (As), phosphorus (P), boron (B), tantalum (Ta), titanium (Ti), silicon (Si), germanium (Ge), sulfur (S) and uranium (U).
• the metallic oxide used in the present invention is the oxide of each metal mentioned above and can provide the gaseous metallic fluoride through the reaction with the F 2 gas or the like.
• Typical examples of the metallic oxide include tungsten oxide (WO 3 ), molybdenum oxide (MoO 3 ), uranium oxide (UO, UO 2 and U 3 O 8 ), arsenic oxide (As 2 O 5 ), antimony oxide (Sb 2 O 5 ), niobium oxide (Nb 2 O 5 ), tantalum oxide (Ta 2 O 5 ), titanium oxide (TiO 2 ) and germanium oxide (GeO 2 ).
• the raw material metal used in the present invention its shape is not particularly limited, but it is preferably in a powdery state having a particle diameter of 1 to 50 ⁇ m, preferably 3 to 20 ⁇ m. This reason is as follows: In the present invention, it is necessary that the metal is mixed with a molding auxiliary and the resulting mixture is then molded under pressure to form molded pieces. In this case, in order to obtain the product in high yield, it is preferable that the metal and molding auxiliary in the molded pieces are mixed as uniformly as possible, and hence the metal is conveniently in the state of the powder. In addition, when the metal is in the state of the powder, the molding under pressure is also easy.
• a solid fluoride which does not react with the fluorine or the like is used as the molding auxiliary.
• This solid fluoride is preferably in the state of a solid even at a temperature at which the metal or the like reacts with the F 2 gas or the like.
• Typical examples of such a solid fluoride include metallic fluorides of the group IA such as lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), rubidium fluoride (RbF) and cesium fluoride (CsF); metallic fluorides of the group IIA such as beryllium fluoride (BeF 2 ), magnesium fluoride (MgF 2 ), calcium fluoride (CaF 2 ), strontium fluoride (SrF 2 ) and barium fluoride (BaF 2 ); metallic fluorides of the group IIIB such as aluminum fluoride (AlF 3 ), gallium fluoride (GaF 3 ), indium fluoride (InF 3 ) and thallium fluoride (TlF 3 ); and a double salt such as aluminum sodium fluoride (Na 3 AlF 6 ). They may be used singly or in combination.
• the solid metallic fluoride is mixed with the metal or the like and is then molded under pressure, it preferably takes a powdery state having a particle diameter of about 1 to 20 ⁇ m, as in the case of the metal or the like.
• the metal is mixed with the solid metallic fluoride which is the molding auxiliary, and the resulting mixture is then molded under pressure.
• the amount of the metal or the like in the mixture is in the range of 30 to 70% by weight based on the total weight of both the metal and the molding auxiliary.
• the mixture of the metal or the like and the solid metallic fluoride is preferably molded under pressure by the use of a tableting machine, and in this case, tableting pressure is in the range of about 0.5 to 10 t/cm 2 , preferably about 1 to 3 t/cm 2 .
• the molded pieces may take any shape, so long as the shape can be obtained by the use of the usual tableting machine, and preferable examples are shapes of cylinder, ring, cubic, sphere, gear wheel shape and ribed shape.
• the size of the molded pieces is not particularly limited, either, and it depends upon the size of the reactor and the handling ease of the molded pieces themselves.
• the molded pieces can take any size, so long as they can be obtained by the use of the tableting machine.
• the molded pieces have an effective diameter of 1/5 to 1/20 of the diameter of the reactor.
• the diameter of the molded pieces is 1/5 to 1/20 of the diameter of the reactor and the height thereof is 1/2 of this diameter, i.e., about 1/10 to 1/40 of the diameter of the reactor. Therefore, when the diameter of the reactor is 10 cm, the diameter and height of the molded pieces are preferably in the range of 5 mm ⁇ to 2 cm ⁇ and in the range of 2.5 mmh to 1 cmh, respectively. Also with regard to the molded pieces having other shapes, these standards can be applied.
• the content of water is low, and therefore it is preferred that the metal and solid fluorine compound are dried to remove water therefrom prior to the molding.
• the material for the reactor in which the metal or the like will be reacted with the F 2 gas or the like, is usually nickel in consideration of anticorrosion to the fluorine or the like.
• the shape of the reactor is not particularly limited, but a cylindrical shape is preferable from the viewpoint of the ease of manufacture.
• the convenient usage of the reactor is as follows: Under the reactor uprightly stood, a perforated plate is disposed, and the reactor is then filled with the above-mentioned molded pieces so that these pieces may be put on the perforated plate. Afterward, the F 2 gas or the like is introduced into the reactor through the perforated plate from its underside. In this case, heating of the reactor is easily carried out by disposing a heater or the like on the outer periphery of the cylindrical reactor.
• the reactor is filled with the molded pieces comprising the metal or the like and the molding auxiliary, as described above. While the molded pieces are heated at a predetermined temperature, the F 2 gas or the like is introduced into the reactor from its underside, so that the metal in the molded pieces is reacted with the F 2 gas or the like, thereby preparing the desired gaseous metallic fluoride.
• a reaction temperature depends upon the kind of gaseous metallic fluoride and the kinds of raw materials. Usually, the reaction temperature is in the range of 150° to 700° C., preferably 200° to 600° C. Typically, the reaction temperatures for the kinds of gaseous metallic fluorides are as shown in Table 1.
• the F 2 gas introduced into the reactor when having a high concentration, is toxic, and therefore it is preferred that the F 2 gas is diluted with an inert gas such as an N 2 gas or Ar gas so as to be used at a concentration of about 5 to 40% by volume.
• an inert gas such as an N 2 gas or Ar gas
• the NF 3 gas In the case of the NF 3 gas, it may be directly used without dilution, but for the ease of handling, the NF 3 gas, when used, may be conveniently introduced thereinto together with a carrier gas of an inert gas such as N 2 or Ar. In this case, the NF 3 gas and carrier gas may be introduced into the reactor separately or in the form of a mixture thereof.
• the heating of the reactor is easily carried out by disposing a heater or the like on the outer periphery of the cylindrical reactor, as described above.
• the pressure is not particularly limited, and needless to say, reduced pressure is also acceptable, but usually the pressure is in the range of atmospheric pressure to about 10 kg/cm 2 .
• a reaction time depends upon the above-mentioned temperature, but it is usually in the range of 1 to 20 hours, preferably about 2 to 10 hours.
• the gaseous metallic fluoride obtained through the reaction contains some of the inert gas used to dilute the F 2 gas or the like and the unreacted F 2 gas or the like, and therefore the fluoride is cooled below its liquefaction temperature to remove the inert gas and F 2 gas or the like therefrom.
• the molded pieces are previously heated in a reducing gas atmosphere and are then brought into contact with the fluorine gas or the like under heating.
• This procedure permits preventing a white solid, which would comprise high-boiling compounds, from adhering to or, in an out, clogging pipes, valves and the like attached to the reactor. Therefore, the above-mentioned embodiment enables the stable operation of the reactor for a long period of time.
• reducing gas a usual gas such as an H 2 gas, NH 3 gas or CO gas can be used.
• the reducing gas can be used at a concentration of 100%, but it is preferably diluted with an inert gas such as an N 2 gas or He gas in consideration of safety.
• a heating temperature depends slightly upon the kind of metal, but is usually in the range of 500° to 850° C.
• the heating temperature is less than 500° C., the formation of the white solid cannot be inhibited perfectly during the reaction with the F 2 gas or NF 3 gas which will be described hereinafter.
• F 2 gas or NF 3 gas which will be described hereinafter.
• energy is only wasted and the reactor filled with the molded pieces must be made from a more expensive material, though the purpose of this invention can be achieved.
• the heating time is in the range of 1 to 100 hours in the case that the metal is used, and it is in the range of about 2 to 500 hours in the case that the metallic oxide is used.
• the completion of the heating operation can be considered to be at the point of time when the water content in the reducing gas at the outlet of the reactor drops to several ppm or less.
• the water content in the molded pieces is low, but additional heating to remove water therefrom is not particularly necessary, since the water in the molded pieces is removed therefrom by the above-mentioned heating.
• the molded pieces which have been heated in the reducing gas atmosphere in this manner are then brought into contact with the F 2 gas or NF 3 gas, thereby preparing the gaseous metallic fluoride.
• the molded pieces which have undergone the heating treatment are preferably handled not to be exposed to an oxidizing atmosphere such as air.
• the heating treatment of the molded pieces is carried out while they are placed in the reactor, and after the heating treatment, the molded pieces are brought into contact with the F 2 gas or NF 3 gas while still placed in the reactor.
• a vertical reactor made of nickel and having an inner diameter of 19 mm and a height of 600 mm was filled in the central portion thereof with the molded pieces.
• an N 2 gas having atmospheric pressure was introduced into the reactor from its underside at a flow rate of 300 Nml/minute for about 2 hours, while the filler layer of the molded pieces was heated at about 100° C.
• an F 2 gas diluted with an N 2 gas and having a concentration of about 30% by volume and atmospheric pressure was introduced into the reactor from its underside at a flow rate of 300 Nml/minute for 3 hours, while the filler layer of the molded pieces was heated at a temperature of 380° to 400° C., whereby reaction was performed.
• a WF 6 -containing gas generated in the reactor was led into a refrigerant trap cooled to a temperature of -80° C., so that the gas was liquefied and collected therein. After the reaction, the trap was evacuated by a vacuum pump to remove the N 2 gas used to dilute the F 2 gas and the unreacted F 2 gas.
• the yield amount of WF 6 was 69 g, and its yield ratio is high, 96% based on fluorine.
• the molded pieces in the reactor maintained the predetermined shape without breaking.
• Example 2 The same procedure as in Example 1 was repeated with the exception that tungsten as the metal was replaced with each metal shown in Table 2 and sodium fluoride as the molding auxiliary was also replaced with each solid metal fluoride shown in Table 2 in each amount shown in Table 2, in order to obtain molded pieces in each amount shown in Table 2 (prior to the molding, each metal and molding auxiliary were dried as in Example 1).
• Example 2 The same reactor as used in Example 1 was filled with the molded pieces in each amount shown in Table 2, and an F 2 gas was introduced thereinto under reaction conditions shown in Table 2. Afterward, following the same procedure as in Example 1, a variety of gaseous metallic fluorides were prepared.
• Yield amounts, yield ratios and Fe contents of the thus obtained gaseous metallic fluoride products are set forth in Table 2.
• the yields in the respective examples were as high as in Example 1, and the metals did not fly about as in Example 1. Additionally, in all the examples, after the completion of the reaction, it was confirmed that the molded pieces did not break.
• Example 2 In the bottom portion of a lateral reactor made from nickel and having a diameter of 38 mm and a length of 600 mm was placed 100 g of the same previously dried metallic tungsten powder as used in Example 1 as uniformly as possible, and the reactor was then heated up to about 100° C. Afterward, an N 2 gas was introduced into the reactor from the left end portion thereof at a flow rate of 300 Nml/minute for about 2 hours, followed by drying metallic tungsten.
• an F 2 gas diluted with an N 2 gas was introduced into the reactor from the left end portion thereof under the same conditions as in Example 1, while the metallic tungsten layer was heated at a temperature of 380° to 400° C. as in Example 1, and a WF 6 -containing gas generated in the reactor was cooled, thereby collecting WF 6 .
• the yield amount of WF 6 was 33 g, and its yield ratio was 46% based on fluorine, which values were so low that they did not reach even the half levels of the values in Example 1.
• the content of Fe in WF 6 was 0.9 ppm, which was indicative that the product was not a little contaminated with the metallic tungsten powder.
• a vertical reactor made of nickel and having an inner diameter of 19 mm and a height of 600 mm was filled in the central portion thereof with the molded pieces.
• an N 2 gas having atmospheric pressure was introduced into the reactor from its underside at a flow rate of 300 Nml/minute for about 2 hours, while the filler layer of the molded pieces was heated at about 100° C.
• the flow rate of the N 2 gas was then lowered to 100 Nml/minute, and while the filler layer of the molded pieces was heated at a temperature of 380° to 400° C.
• an NF 3 gas having atmospheric pressure was introduced into the reactor at a flow rate of 80 Nml/minute, whereby reaction was performed for 2 hours.
• a WF 6 -containing gas generated in the reactor was led into a refrigerant trap cooled to a temperature of -80° C., and the gas was liquefied and collected therein. After the completion of the reaction, the trap was evacuated by a vacuum pump to remove the N 2 gas used as a carrier gas, a secondarily formed N 2 gas and the unreacted NF 3 gas.
• the yield amount of WF 6 was 60 g, and its yield ratio was as high as 94% based on WF 6 .
• the molded pieces in the reactor maintained the predetermined shape without breaking.
• Example 9 The same procedure as in Example 9 was repeated with the exception that tungsten as the metal was replaced with each metal shown in Table 3 and sodium fluoride as the molding auxiliary was replaced with each solid metal fluoride shown in Table 3 in each amount shown in Table 3, in order to obtain molded pieces in each amount shown in Table 3 (prior to the molding, each metal and molding auxiliary were dried as in Example 1).
• Example 9 The same reactor as used in Example 9 was filled with the molded pieces in each amount shown in Table 3, and the molded pieces were dried under the same conditions as in Example 9. Afterward, an NF 3 gas and carrier gas were introduced thereinto under reaction conditions shown in Table 3, and following the same procedure as in Example 9, a variety of gaseous metallic fluorides were prepared.
• a lateral reactor made of nickel and having a diameter of 25 mm and a length of 600 mm was placed 100 g of the same previously dried metallic tungsten powder as used in Example 9 as uniformly as possible, and the reactor was then heated up to about 100° C. Afterward, an N 2 gas having atmospheric pressure was introduced into the reactor from the left end portion thereof at a flow rate of 300 Nml/minute for about 2 hours, followed by drying metallic tungsten.
• the flow rate of the N 2 gas was lowered to 100 Nml/minute and an NF 3 gas having atmospheric pressure was introduced into the reactor from the left end portion thereof at a flow rate of 80 Nml/minute under the same conditions as in Example 9, while the metallic tungsten layer was heated at a temperature of 380° to 400° C. as in Example 9, whereby reaction was performed for 2 hours.
• a WF 6 -containing gas generated in the reactor was cooled to collect WF 6 in the same manner as in Example 9.
• the yield amount of WF 6 was 28 g, and its yield ratio was 44% based on fluorine, which values were so low that they did not reach even the half levels of the values in Example 9.
• the content of Fe in WF 6 was 1.2 ppm, which was indicative that the product was not a little contaminated with the metallic tungsten powder.
• a vertical reactor made of nickel and having an inner diameter of 19 mm and a height of 600 mm was filled in the central portion thereof with the molded pieces.
• an N 2 gas having atmospheric pressure was introduced into the reactor from its underside at a flow rate of 300 Nml/minute for about 2 hours, while the filler layer of the molded pieces was heated at about 120° C.
• an F 2 gas diluted with the N 2 gas and having a concentration of about 20% by volume and atmospheric pressure was introduced into the reactor from its underside at a flow rate of 300 Nml/minute for 3 hours, whereby reaction was performed.
• a WF 6 -containing gas generated in the reactor was led into a refrigerant trap cooled to a temperature of -80° C., and the gas was liquefied and collected therein. After the completion of the reaction, the trap was evacuated by a vacuum pump to remove the N 2 gas used to dilute the F 2 gas, the unreacted F 2 gas and a secondarily formed O 2 gas which slightly remained in the liquefied WF 6 .
• the yield amount of WF 6 was 45 g, and its yield ratio was as high as 94% based on fluorine.
• the molded pieces in the reactor maintained the predetermined shape without breaking.
• Example 16 The same procedure as in Example 16 was repeated with the exception that tungsten oxide as the metallic oxide was replaced with each metallic oxide shown in Table 4 and sodium fluoride as the molding auxiliary was replaced with each solid metal fluoride shown in Table 4 in each amount shown in Table 4, in order to obtain molded pieces in each amount shown in Table 4 (prior to the molding, each metallic oxide and molding auxiliary were dried as in Example 16).
• Example 16 The same reactor as used in Example 16 was filled with the molded pieces in each amount shown in Table 4, and an F 2 gas was introduced thereinto under reaction conditions shown in Table 4, and following the same procedure as in Example 16, a variety of gaseous metallic fluorides were prepared.
• a lateral reactor made from nickel and having a diameter of 25 mm and a length of 600 mm was placed 100 g of the same previously dried tungsten oxide powder as used in Example 16 as uniformly as possible, and the reactor was then heated up to about 100° C. Afterward, an N 2 gas was introduced into the reactor from the left end portion thereof at a flow rate of 300 Nml/minute for about 2 hours, followed by drying tungsten oxide.
• an F 2 gas diluted with an N 2 gas was introduced into the reactor from the left end portion thereof under the same conditions as in Example 16, while the tungsten oxide layer was heated at a temperature of 380° to 400° C. as in Example 16, and a WF 6 -containing gas generated in the reactor was then cooled to collect WF 6 .
• the yield amount of WF 6 was 22 g, and its yield ratio was 46% based on fluorine, which values were so low that they did not reach even the half levels of the values in Example 16.
• the content of Fe in WF 6 was 0.8 ppm, which was indicative that the product was not a little contaminated with the tungsten oxide powder.
• a vertical reactor made of nickel and having an inner diameter of 25 mm and a height of 600 mm was filled in the central portion thereof with the molded pieces.
• an N 2 gas having atmospheric pressure was introduced into the reactor from its underside at a flow rate of 300 Nml/minute for about 2 hours, while the filler layer of the molded pieces was heated at about 100° C.
• the flow rate of the N 2 gas was then lowered to 100 Nml/minute, and while the filler layer of the molded pieces was heated at a temperature of 380° to 400° C.
• an NF 3 gas having atmospheric pressure was introduced into the reactor at a flow rate of 70 Nml/minute, whereby reaction was performed for 2 hours.
• a WF 6 -containing gas generated in the reactor was led into a refrigerant trap cooled to a temperature of -80° C., and the gas was liquefied and collected therein. After the completion of the reaction, the trap was evacuated by a vacuum pump to remove the N 2 gas used as a carrier gas, a secondarily formed N 2 gas and O 2 gas and the unreacted NF 3 gas.
• the yield amount of WF 6 was 52 g, and its yield ratio was as high as 93% based on fluorine.
• the molded pieces in the reactor maintained the predetermined shape without breaking.
• Example 23 The same procedure as in Example 23 was repeated with the exception that tungsten oxide as the metallic oxide was replaced with each metallic oxide shown in Table 5 and sodium fluoride as the molding auxiliary was replaced with each solid metal fluoride shown in Table 5 in each amount shown in Table 5, in order to obtain molded pieces in each amount shown in Table 5 (prior to the molding, each metallic oxide and molding auxiliary were dried as in Example 23).
• Example 23 The same reactor as used in Example 23 was filled with the molded pieces in each amount shown in Table 5, and the molded pieces were dried under the same conditions as in Example 23. Afterward, an NF 3 gas and carrier gas were introduced thereinto under reaction conditions shown in Table 5, and following the same procedure as in Example 23, a variety of gaseous metallic fluorides were prepared.
• a lateral reactor made of nickel and having a diameter of 25 mm and a length of 600 mm was placed 100 g of the same previously dried tungsten oxide powder as used in Example 23 as uniformly as possible, and the reactor was then heated up to about 100° C. Afterward, an N 2 gas having atmospheric pressure was introduced into the reactor from the left end portion thereof at a flow rate of 300 Nml/minute for about 2 hours, followed by drying tungsten oxide.
• the flow rate of the N 2 gas was then lowered to 100 Nml/minute and an NF 3 gas having atmospheric pressure was introduced into the reactor from the left end portion thereof at a flow rate of 70 Nml/minute under the same conditions as in Example 23, while the tungsten oxide layer was heated at a temperature of 380° to 400° C., whereby reaction was performed for 4 hours. Afterward, a WF 6 -containing gas generated in the reactor was cooled to collect WF 6 in the same manner as in Example 23.
• the yield amount of WF 6 was 48 g, and its yield ratio was 43% based on fluorine, which values were so low that they did not reach even the half levels of the values in Example 23.
• the content of Fe in WF 6 was 1.0 ppm, which was indicative that the product was not a little contaminated with the tungsten oxide powder.
• a vertical reactor made of nickel and having an inner diameter of 75 mm and a height of 1,000 mm was filled in the central portion thereof with the molded pieces.
• an N 2 gas (diluent gas) and H 2 gas (reducing gas) having atmospheric pressure were both introduced into the reactor from its underside at a flow rate of 300 Nml/minute for about 10 hours, while the filler layer of the molded pieces was heated at about 700° C., whereby the molded pieces were thermally treated.
• the H 2 gas in the reactor was perfectly replaced with the N 2 gas.
• the flow rate of the N 2 gas was lowered to 100 Nml/minute, and while the filler layer of the molded pieces was heated at a temperature of 380° to 400° C., an NF 3 gas having atmospheric pressure was introduced into the reactor at a flow rate of 100 Nml/minute, whereby reaction was performed for 50 hours.
• a WF 6 -containing gas generated in the reactor was led into a collector vessel cooled to a temperature of -80° C., so that the gas was liquefied and collected therein.
• the collector vessel was evacuated by a vacuum pump to remove the N 2 gas used as a carrier gas, a secondarily formed N 2 gas and the unreacted NF 3 gas.
• the yield amount of WF 6 was 1,960 g, and its yield ratio was as high as 98% based on the NF 3 gas.
• WF 6 was removed from the collector vessel by distillation at a little higher temperature than the boiling point of WF 6 , and the interior of the collector vessel was then observed. However, it was confirmed that neither the white solid nor metallic tungsten were present therein.
• Example 30 The same procedure as in Example 30 was repeated with the exception that metallic tungsten was replaced with each simple metal shown in Table 6, and NaF as the molding auxiliary was replaced with each solid metallic fluoride shown in Table 6 in each amount shown in Table 6 by the use of each tableting pressure shown in Table 6, in order to obtain molded pieces.
• Example 30 The same reactor as used in Example 30 was filled with the molded pieces, and a reducing gas and dilute gas shown in Table 6 were introduced into the reactor under reaction conditions shown in Table 6 as in Example 30 to thermally treat the molded pieces.
• yield amounts and yield ratios of the thus obtained gaseous metallic fluoride products are set forth in Table 6, and the yields in the respective examples were as high as in Example 30. Additionally, in the same manner as in Example 30, it was inspected whether or not the simple metal and a white solid were present in the collected gaseous metallic fluorides. As a result, their presence was not confirmed.
• Example 30 The reactor used in Example 30 was filled with 3 kg of the molded pieces obtained in the same manner as in Example 30, and while the filler layer of the molded pieces was heated at a temperature of 700° C., an N 2 gas as an inert gas having atmospheric pressure was then introduced into the reactor at a flow rate of 300 Nml/minute until the water content in the gas at an outlet of the reactor had reached 5 ppm, whereby the water in the molded pieces was removed therefrom.
• an N 2 gas as an inert gas having atmospheric pressure was then introduced into the reactor at a flow rate of 300 Nml/minute until the water content in the gas at an outlet of the reactor had reached 5 ppm, whereby the water in the molded pieces was removed therefrom.

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